Wednesday, June 28, 2017

Whether it's balancing on a blade of grass or taking on the appearance of frozen smoke, aerogels have been blowing us away with their amazing properties in recent years. And just when you thought they couldn't get any freakier, researchers have created a graphene aerogel that can support over 6,000 times its own weight.

Thalia dealbata Fraser ex Roscoe credit: wikipedia

Along with being super strong, the new aerographene is bendy, conductive, and mimics the structure of a plant stem. The unique properties of the material could make it an ideal component in flexible electronics such as smart windows, curved TV screens, and printable solar panels.

Speaking with ScienceAlert, Hao Bai . a materials engineer from Zhejiang University, says the graphene aerogel is unique from other aerogels available.

Dr. Hao Bai Tomsia Biomaterials Research Group credit: tomsia

"Learning from nature always offers new insights for developing new materials and technology," says Bai. "Our graphene aerogel is different from current aerogels in both microstructures and properties."Weighing a minuscule 0.16 milligrams per cubic centimetre, graphene aerogel is 7.5 times lighter than air and about 1000 times less dense than water. This stuff is so light that you can balance it on a fluffy dandelion head or on the stamen of a flower. Out of all the aerogels, graphene aerogel is the least dense and considered one of the lightest solid materials on Earth.Apart from blowing our minds, aerogels are already proving useful for a wide variety of applications, from cleaning up oil spills to creating high-energy batteries. Researchers have even managed to convert sunlight into water vapour at room temperature using graphene aerogel, which makes it possible to turn wastewater into drinkable water.But when it comes to moving machine parts, flexible sensors, and bendable energy storage devices, researchers have struggled to create aerogels that have both the strength and resilience required for these applications."Strength and resilience are usually mutually exclusive in regular aerogels," Bai explains. "There is a high demand for strong and resilient aerogels in many important fields, but it is very difficult to achieve both of these properties."In recent years, we've seen several attempts to achieve these properties in graphene aerogels, including through the use of 3D printing and freeze-drying. The problem with these processes is that they only produce graphene aerogels with a random architectural structure, which doesn't provide robust strength and resilience.Looking at the natural world, the secret to the strength and bendiness of porous materials like plant stems comes down to how the material is arranged at the nanoscale. Even if the material itself is weak and porous, the highly organised arrangement of the material makes it strong and flexible."Many natural materials have developed unprecedented properties by building complex multiscale architectures," Bai says. "We wondered whether we could mimic these features to create an aerogel that is both strong and resilient." To find out, Bai and his team turned to the powdery alligator-flag (Thalia dealbata), a hardy aquatic plant native to South America and Mexico. Even though the stem of this plant is slender and porous, it can withstand frequent wild winds thanks to its grid-like layered microstructure.

Powdery Thalia (Thalia dealbata) Credit: Garden Supply Co

Taking cues from the plant's complex structure, the team used bidirectional freezing to mimic its architecture in graphene aerogel.First, graphene oxide particles are dispersed in water, which form sheets as the liquid freezes.Once completely frozen, the graphene oxide sheets form a three-dimensional network similar to the structure of ice crystals.Finally, thermal reduction and sublimation produced graphene aerogel that mirrored the bridged layers of the powdery alligator-flag stem.Next, the team put the aerogel through a series of compression tests to see whether its architecture produced strength and resilience. After 1,000 compressive cycles the researchers discovered that the graphene aerogel was capable of supporting over 6,000 times its own weight and spring back to its original state. The material also retained 85 per cent of its strength before compression was applied.This is a significant jump from aerogels with a random architecture, which tend to retain just 45 per cent of their original strength after only 10 compressive cycles.Although the enormous strength and resilience of the aerogel is amazing all on its own, the researchers also wanted to know whether the material was conductive under compression.The team placed the aerogel in a circuit with an LED, and applied different compression strains. Sure enough, they found that the aerogel remained conductive even when compressed, indicating that it could play a role in flexible electronics and sensors.Now that the researchers have finally created a graphene aerogel that is strong, resilient and conductive, the next step is figuring out whether nature can be used as a reference for developing other kinds of aerogels, such as cellulose-based or polymer-silica composites."Learning from natural models will definitely help to develop new materials," Bao told ScienceAlert. "The challenges still remain in how much we can discover and understand nature's secrets, and if we can really mimic nature with synthetic approaches."We can only dream of what nature will help us design next.Other articles on the same theme:

Saturday, June 24, 2017

Stephen Hawking says humanity must find a new home Max Alexander/Starmus

The renowned physicist Stephen Hawking is working on a spacecraft that can travel at a fifth of the speed of light – meaning it could reach the nearest star and send back images of a suspected ‘Second Earth’ within 25 years – in a bid to save humanity.In a speech at the Starmus Festival, Professor Hawking warned humans must soon colonise another planet if we are to survive.One explanation for why Earth has not been contacted by an advanced civilisations from another part of the Universe is that every time ‘intelligent’ life evolves it annihilates itself with “war, disease and weapons of mass destruction”, he said.And in addition to the chance that we will meet this fate, Professor Hawking said the planet had become too small for our burgeoning population with its “physical resources … being drained at an alarming rate”. Climate change, an asteroid strike or some other kind of cataclysmic cosmic event also pose significant threats.The proposed spacecraft, called a Star Chip, would be just a few centimetres in size with a lightsail weighing a few grams. It would be powered by an array of lasers based on Earth that would drive the tiny probe “on a beam of light” at about 100 million miles an hour, a fifth of light speed.

Credit: duluthnewstribune

“Such a system could reach Mars in less than an hour, reach Pluto in days, pass Voyager [the space probe launched in 1977] in under a week, and reach Alpha Centauri in just over 20 years,” Professor Hawking said.“Once there, the nano craft could image any planets discovered in the system, test for magnetic fields and organic molecules, and send the data back to Earth in another laser beam. “This tiny signal would be received by the same array of dishes that were used to transit the launch beam, and return is estimated to take about four light years.

And he admitted: “Of course, this would not be human interstellar travel, even if it could be scaled up to a crewed vessel. It would be unable to stop.

“But it would be the moment when human culture goes interstellar, when we finally reach out into the galaxy. And if Breakthrough Star Shot should send back images of a habitable planet orbiting our closest neighbour, it could be of immense importance to the future of humanity.”

Because it is travelling so fast any pictures taken by a camera on the Space Chip would be “slightly distorted” due to the effects of special relativity, as first described by Albert Einstein. This would be the first time anything has travelled fast enough to see such effects.

And extolling the virtues of the human attribution – “out most powerful attribute” – he said: “With this, we can roam anywhere in space and time. And I do.

“We can witness nature’s most exotic phenomena while in a car, snoozing in bed, or pretending to listen to someone boring at a party. And I do.”

Sunday, June 18, 2017

Neuroscientists have used a classic branch of maths in a totally new way to peer into the structure of our brains. What they've discovered is that the brain is full of multi-dimensional geometrical structures operating in as many as 11 dimensions.

We're used to thinking of the world from a 3-D perspective, so this may sound a bit tricky, but the results of this new study could be the next major step in understanding the fabric of the human brain - the most complex structure we know of.
This latest brain model was produced by a team of researchers from the Blue Brain Project, a Swiss research initiative devoted to building a supercomputer-powered reconstruction of the human brain.

The team used algebraic topology, a branch of mathematics used to describe the properties of objects and spaces regardless of how they change shape. They found that groups of neurons connect into 'cliques', and that the number of neurons in a clique would lead to its size as a high-dimensional geometric object.

"We found a world that we had never imagined," says lead researcher, neuroscientist Henry Markram from the EPFL institute in Switzerland.

"There are tens of millions of these objects even in a small speck of the brain, up through seven dimensions. In some networks, we even found structures with up to 11 dimensions."

Just to be clear - this isn't how you'd think of spatial dimensions (our Universe has three spatial dimensions plus one time dimension), instead it refers to how the researchers have looked at the neuron cliques to determine how connected they are.

"Networks are often analysed in terms of groups of nodes that are all-to-all connected, known as cliques. The number of neurons in a clique determines its size, or more formally, its dimension," the researchers explain in the paper.

Human brains are estimated to have a staggering 86 billion neurons, with multiple connections from each cell webbing in every possible direction, forming the vast cellular network that somehow makes us capable of thought and consciousness.

With such a huge number of connections to work with, it's no wonder we still don't have a thorough understanding of how the brain's neural network operates. But the new mathematical framework built by the team takes us one step closer to one day having a digital brain model.

To perform the mathematical tests, the team used a detailed model of the neocortex the Blue Brain Project team published back in 2015. The neocortex is thought to be the most recently evolved part of our brains, and the one involved in some of our higher-order functions like cognition and sensory perception.

After developing their mathematical framework and testing it on some virtual stimuli, the team also confirmed their results on real brain tissue in rats.

According to the researchers, algebraic topology provides mathematical tools for discerning details of the neural network both in a close-up view at the level of individual neurons, and a grander scale of the brain structure as a whole.

By connecting these two levels, the researchers could discern high-dimensional geometric structures in the brain, formed by collections of tightly connected neurons (cliques) and the empty spaces (cavities) between them.

"We found a remarkably high number and variety of high-dimensional directed cliques and cavities, which had not been seen before in neural networks, either biological or artificial," the team writes in the study.

"Algebraic topology is like a telescope and microscope at the same time," says one of the team, mathematician Kathryn Hess from EPFL.

"It can zoom into networks to find hidden structures, the trees in the forest, and see the empty spaces, the clearings, all at the same time."

Those clearings or cavities seem to be critically important for brain function. When researchers gave their virtual brain tissue a stimulus, they saw that neurons were reacting to it in a highly organised manner.

"It is as if the brain reacts to a stimulus by building [and] then razing a tower of multi-dimensional blocks, starting with rods (1D), then planks (2D), then cubes (3D), and then more complex geometries with 4D, 5D, etc," says one of the team, mathematician Ran Levi from Aberdeen University in Scotland.

"The progression of activity through the brain resembles a multi-dimensional sandcastle that materialises out of the sand and then disintegrates."

These findings provide a tantalising new picture of how the brain processes information, but the researchers point out that it's not yet clear what makes the cliques and cavities form in their highly specific ways.

And more work will be needed to determine how the complexity of these multi-dimensional geometric shapes formed by our neurons correlates with the complexity of various cognitive tasks.

But this is definitely not the last we'll be hearing of insights that algebraic topology can give us on this most mysterious of human organs - the brain.

About me

I'm working on a theory for some time in trying to combine science with religion, looking for an answer to the question

"What is the purpose of life in Creation? Is it possible for life to be an unintended consequence of our Universe?

Finally due to space,science and exploration throughout the Universe we got everyone to agree with the fact that we are not the only planet with life. My blog is full of interesting articles about Creation of the Universe with all his laws, NASA's Missions, History, Science, Physics, Health, Nature, Ancient origins and Culture.